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` STEAM AGTUATBD VALVE. No. 295,669. c Patented Mar. 25, 1884.

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UNITED STATES PATENT OFFICE.

DAVID F. NISBET, OF SYRACUSE, NEV YORK.

STEAM-ACTUATE'D VALVE.

SPECIFICATION forming part of Letters Patent No. 295,669, dated March 25, 1884.

Application tiled November 2S, i883. (No model.)

0 ctZZ whom it may concern.-

Be it known that I, DAVID F. NIsBET, of Syracuse, in the county of Onondaga, in the State of New York, have invented new and useful Improvements in Steam-Actuated Valves, of which the following, taken in connection with the accompanyingdrawings, is a full, clear, and exact description.

This invention consists ina novel construction and combination of the valve of a steamcylinder and means for actuating said valve, whereby the operation of the valve is rendered positive without-,the employment of a balancewheeLand-with a comparatively slight motion of the valve-gear, and consequently with a materially reduced friction and wear of the latter; and, furthermore, the said valve-gear is rendered safeA from liability of disarrangement, and easy of access for repairs or adjustment, all as hereinafter more fully described, and specifically set forth in the claims.

In the annexed drawings,.Figure lis a longitudinal section of my invention. Fig. 2is a transverse section on line :v :v,13`ig. '1; and Fig. 3 is a detached isometric view of the main actuating mechanism of the valve.

' S represents the steam-chest, mounted on the steam-cylinder of an engine or pump, and provided with the usual steam and exhaust ports,

m and m'.

A is an ordinary slide-valve, which I designate the main valve, for the reason hereinafter explained, said valve being arranged to reciprocate over the ports m m m, to admit the steam to the cylinder and pass the exhauststeam from the same in the usual manner. The steam-chest S has its interior formed with end extensions, S', preferably of cylindrical form, and in each of said extensions is fitted a steam-tight piston, f. v Said pistons are fixed to opposite ends of a rod, a, which is extended through yokes b on the main valve A, and holds said valve securely between the pistons f f by collars t, fixed to or formed on the rod a be tween the pistonand valve.

B denotes a supplemental valvein the form of an annular disk, fitted steam-tight in an opening, E,` in the side of the steam-chest. Said supplemental valve is rigidly attached to a rock-shaft, C, which is extended across the main valve A, midway between theyokes thereof, and is journaled in the opposite side of the ings. To the rock-shaft C' are alsoiirmly attached two cams, D D, which project radially at corresponding angles from said shaft. By means of longitudinal parallel ribs c c, projecting from the top of the valve A at the sides of Athe cams D D, the roclcshaft is prevented from moving longitudinally, and is thus eoniined to its bearings in the steam-chest.

On the inner side of each of the yokes are `two shoulders ,or projections, e e, which are in range with the cams D D, so as to encounter with the same during the oscillation of the rock-shaft, the alternateencounter with the projections at opposite sides of the rock-shaft imparting a rectilinear reciprocating motion to the main valve A. The cams D and projections c are so proportioned as to allow the valve to be carried only part way its requisite stroke, the stroke being completed by the'fol-v lowing instrumentalities:

The annular supplemental valve B, seated in a circular opening in the side of the steamchest, as before described, is provided in the lower portion of its peripheral face with a` groove or channel, r, which is extended about one-third the circumference of the valve B, and the upper portion of the supplemental valve is provided with two recesses or passages, p p, which extend to the periphery of i.

the supplemental valve.

Through the side wall of the steam-chest are extended channels or ducts fi, g, and g, one of which reaches from the supplemental valve B to the exhaust-port m of the cylinder, and the other two ducts are extended from the supplemental valve to the ends of the steam-chest extensions S. The channel r and passages p p steam-chest, as shown in Fig. 2 of the drawin the supplemental valve B and the ends of the ducts t', g, and g, adjacent to the supplemental valve, are arranged in such positions in relation to each other that when the rock-shaft l IOO steam-chest to the back of the other piston f, as indicated by arrows in Fig. 1 of the drawings. This relief of the piston at one end of the main valve and the application of steampressure to the piston on the opposite end of said valve causes the latter to be moved to the end of its requisitestroke. The oscillation of the supplemental valve B brings the passages thereof alternately in communication with the ducts leading to opposite ends of the steamchest, The ducts r/ intersect the steam-chest extensions S a sufficient distance from the end thereof to cause the end of the duct to be closed by the piston f before it has reached the end of its stroke, thereby coniining a portion of the steam in Ythe end of the steamchest extensions, to form a cushion for receiving the thrust of the approaching piston. The rock-shaft C receives its motion by means of an arm, l, attached to the said shaft, and connected with the main piston-rod in any suitable manner to partake the requisite motion therefrom.

It will be observed that the described means for operating the main valve dispense with thc flywheel, and are simple in construction, positive in their action, and while secure in their arrangement they are, nevertheless, easy of access for repairs, renewal, or adjustment. In the reverse motion of the rock-shaft the Cams D move the main valve suiiiciently to carry the piston fclear of the end of the ducts g, and simultaneously bring the passage p of the supplemental valve in `coincidence with the aforesaid duct to admit steam through the same to the backof the receding piston, and this application of steam propels the piston to the end of its stroke.

It will be observed that by the described arrangement asingle du ct serves to convey steam to and from the end of the steam-chest extension.

Having described my invention, .what I claimas new, and desire to secure by Letters Patent, is-

1. In combination with a slide-valve of a steam-engine, a steam-chest having its interior formed with end-extension pistons on the ends of the valve, a rock-shaft having cams adapted to move the valve part way its stroke, a supplemental Valve connected With the rockshaft and provided with steam and exhaust passages, and auxiliary steam and exhaust channels extended i'rom the supplemental valve, respectively, to the ends of the steam-chest extensions and to the exhaust-port of the steamcylinder, said parts being constructed and arranged in such relation to each other that the main valve will move part way its stroke synchronous with the first movement of the supplemental valve and complete the stroke by the pressure of steam admitted to the steamchest extensions by the supplemental valve, substantially as specified.`

2. In combination witha slide-.valve of a steam-cylinder, a steam-chest provided in the center of one of the sides with an annular opening, the exhaust-port of the cylinder, a rock-shaft extended through the center of said cavity, a disk mounted on the rock-shaft and fitted to the aforesaid cavity, and having in its periphery recesses adapted to communicate with the aforesaid ducts, and cams attached to the rock-shaft and adapted to carry the valve par-t way its stroke, substantially as described and shown.

3. In combination with the main valve provided with pistons at opposite ends, the rockshaft provided with cams D D, the supplemental valve provided with passages r and p p, and single ducts extended from the supplemental valve, respectively, to opposite ends of the steam-chest and to the exhaust-port, substantially as described and shown.

In testimony whereof I have hereunto signed my name and affixed my seal, in the presence of two attesting witnesses, at Syracuse, in the county of Onondaga, in the State of New York, this 17th day of November, 1883.

DAvID E. NisBET. [L s] Vitnesses:

FREDERICK H. GIBBs, CHARLES H. DUELL. 

